In recent years, bipartisan efforts to scale back the United States’s unprecedented reliance on incarceration had started to show some signs of success, with prison populations falling in nearly half the states nationwide between 2010 and 2015. Yet in 2016, Trump pulled off an upset victory in part by tapping into Americans’ continued fear of violence, relying aggressively on “tough on crime” rhetoric. Despite all the chaos currently embroiling his Administration, many are understandably nervous that his presidency could still derail these relatively nascent reform efforts. Thankfully, I think (and hope) these fears are likely misplaced, and contrary to many commentators I do not expect that the Trump Administration will have much impact on reform.

Many of you will already know the story behind the recent prison reform efforts. In the 1970s, the U.S. incarceration rate was comparable to that of other western countries, at about 100 per 100,000 (for comparison, the rate in England and Wales in 1970 was approximately 80 per 100,000). Over the next 35 years, however, it steadily and relentlessly rose, essentially quintupling by the 2000s. We now have the world’s highest incarceration rate—and, to quote a hoary statistic, we are home to 5 percent of the world’s population but roughly 25 percent of its prisoners. The countries that come close to us are mostly autocratic or semi-autocratic regimes including Russia, Cuba, and Turkmenistan.

After several decades of low and falling crime rates, however, the budget-eviscerating 2008 financial crisis appears to have produced a genuinely bipartisan effort to scale back incarceration (and its costs). And in 2010, total prison populations dropped for the first time since 1972; by 2015, state and federal prison populations had fallen by a bit more than 5 percent. This was not a dramatic drop, but after so many years of unceasing growth, it was an accomplishment to celebrate, and one that indicated reforms like expanding parole and cutting sanctions for certain crimes were starting to succeed.

Reform’s biggest vulnerability, however, is that Americans remain fearful of crime, even as crime rates have dropped to near-historic lows. And from its start, Donald Trump’s campaign aimed to stoke those fears. He launched his campaign with a speech vilifying immigrants as violent criminals, and his inauguration address replaced Reagan’s “morning in America” with “American carnage.” He soon after nominated Jeff Sessions, a staunch opponent of criminal justice reform, as his attorney general. Sessions, in turn, has persistently advocated for 1980s-style “tough on crime” policies, such as insisting federal prosecutors impose the toughest prison sentences they can.

Yet I still remain cautiously hopeful. The Administration’s rhetoric certainly doesn’t help matters, but in the end, the federal government has very little control over criminal justice. About 90 percent of all prisoners—and a far greater percentage of those in jails, on probation, or who are arrested every year—are handled by states and counties, not by the federal government. And the federal government cannot directly tell states what to do when it comes to dealing with these individuals. For example, they cannot make local governments change their laws, enforce existing laws more aggressively, or determine who is released on parole or who is sent back to prison.

The federal government has only two indirect tools at it disposal: incentive grants and the bully pulpit. And neither is as powerful as many people think.

Take grants. State and local governments spend about $200 billion per year on criminal justice (about $100 billion on policing, $50 billion on prisons, $30 billion on jails, and $20 billion on courts and other expenses). Federal criminal justice grants come to about 2-3 percent of that total. So these grants are not irrelevant, but the amounts are likely not large enough of a carrot to change behavior all that much.

In fact, states have a history of paying seemingly little attention to fiscal offers and threats from the federal government. When the federal government offered states up to $10 billion to toughen their sentencing laws as part of the 1994 Violent Crime Control Act, most states ignored the program; the federal government eventually paid out less than $3 billion of the $10 billion on offer. Conversely, when the federal government threatened in 2006 to strip states of some grants if they did not adopt specific sex offender registry requirements, almost two-thirds of states chose to lose funding rather than comply—most because the costs of compliance were too high, but at least one (Nebraska) out of opposition to the policy itself.

As for the bully pulpit, it’s surely the case that harsh, tough-on-crime rhetoric will make reformers’ jobs somewhat tougher, but the overall impact is likely to be slight. Prison growth is driven, first and foremost, by local county prosecutors, and these prosecutors are focused almost entirely on local issues and interests and politics.

A striking example: In 1973, New York State adopted the remarkably harsh “Rockefeller Drug Laws,” named after then-Governor Nelson Rockefeller, who pushed for these laws partly in response to rising drug-related violence, but also to further his presidential aspirations. Remarkably, though, by 1984 the number of people in prison in New York on drug charges had barely changed. Local prosecutors essentially ignored the law—and, by extension, Rockefeller’s bully pulpit.

That all changed in 1984, when the number of people in prison for drugs rose sharply, and continued to rise until the mid-1990s. This still had little to nothing to do with state issues and, again, everything to do with local crime. In 1984, crack, and the violence associated with its markets, tore across New York, and local prosecutors cracked down in response.

New York has since reformed the Rockefeller Laws twice, in 2004 (weakly) and in 2009 (more significantly). Yet the number of people in state prison for drugs started to decline years before the reforms were passed—in 1995—the two reforms did not appear to affect that decline at all. Again, local prosecutors changed their behavior in response to improving local conditions, consistently paying little attention to what was happening in Albany. If New York prosecutors have been willing to ignore Albany, why would they pay attention to what is being said by even more remote politicians in Washington, D.C.?

More than likely, they won’t; what prosecutors care about is their county electorates. And, at least in more populous counties, local politics still seem to favor reform. The 2016 election provides several interesting examples of this. In red and blue states alike, voters frequently approved smart-on-crime initiatives (including two focused on decriminalizing drugs in strongly pro-Trump Oklahoma) and elected reform-minded prosecutors in places ranging from Corpus Christi and Dallas in Texas, to Jacksonville, Florida, to Chicago, Illinois.

In some ways, the localism of prison growth acts a bulwark against the Trump Administration, since no single federal law or executive order can tell police and prosecutors and governors what to do. Federalism, here, is a shield.

Of course, the flip side of this is easy to see: Just as no single federal law can derail reform, no single federal law can end mass incarceration. For both good and ill, to truly reform the criminal justice system, we need to change the incentives of nearly 2,500 locally elected prosecutors scattered across counties big and small. Some reforms can be implemented statewide by the legislature, like adopting guidelines that regulate the sorts of charges prosecutors can file or plea deals they can demand. But many changes will need to come by convincing locally elected prosecutors to use the discretion they already have in less punitive ways, like seeking cash bail less often. A more local focus may be more time consuming, but it can also produce change more rapidly. New laws take time to debate and implement, but a local prosecutor can change how he uses his discretion overnight.

To be clear, there are many of ways in which prison reform can fail, and whether the decreasing incarceration levels we’ve seen since 2010 is part of a trend or just a brief hiccup remains to be seen. Success or failure, however, will be determined by local actors and issues, not by the alarmist claims and posturing coming from the Trump Administration.